Self-cleaning screen for material handling apparatus



July 19, 1955 s. BOGATY 2,713,213

SELF-CLEANING SCREEN FOR MATERIAL HANDLING APPARATUS Filed Feb. l5, 19543 Sheets-Sheet l /7 lg l@ i July 19, 1955 s. BOGATY 2,713,213

SELF-CLEANING SCREEN FOR MATERIAL HANDLING APPARATUS Filed Feb. l5, 19545 Sheets-Sheet 2 `@QOOO COO/@@@QGG/Q@ July 19, 1955 s. BoGATY 2,713,213

SELF-CLEANING SCREEN FOR MATERIAL HANDLING APPARATUS Filed Feb. l5, 19545 Sheets-Sheet 3 United States hatent fiee Patented July SELF-CLEAr THGSCREEN FR MTERAL NBLING APPAITUS Stanislaus Bogaty, hilndelphia, Pm,assigner to Proctor and Schwartz, Inc., Phiiadelphia, Pa., a corporationof Pennsylvania Application February l5, 1954, Serial No. @0,335

i3 Claims. (Cl. 34m-3?.)

The present invention relates to new and useful irnprovements in selfcleaning screens for material handling apparatus and more particularlyto new and useful improvements in self-cleaning screens which may hepositioned above a conveyor transporting fine material through a dryeror liite equipment and prevent the material from circulating through theapparatus with the drying or other treating medium.

ln the treating and drying of tobacco in dryers and other equipmenthaving circulation of the drying or other treating medium both up anddown through the material being treated, the standard procedure has beento reduce the volume of the medium circulating up through the materialto such a point where particles of the material being treated will notbecome entrained in the flow of the treating medium. This practice isprevalent even though a necessarily decreased output results from thisreduced circulation because the use of a more intensive circulationwould require a screen to prevent the small particles of material frombeing circulated through the material treating apparatus along with thedrying medium.

The only presently existing hold-down screens are of the stationary typewhich become badly clogged after a few hours of operation and theconveyor type which must be girt supported and are too expensive to beinstalled in most types of equipment.

With the foregoing in mind the principal object of the present inventionis to provide a self-cleaning screen readily adaptable for installationin new or presently existing material handling equipment which willincrease the output of the apparatus.

Another object of the present invention is to provide a novelcontinuously operating self-cleaning screen particularly adapted for usein drying apparatus such as, for example, tobacco dryers wherein thecirculation of drying medium is in dierent directions in alternatecompartments in the dryer.

A further object of the present invention is to provide a self-cleaningtobacco screen of the type set forth above which will increase thecapacity and output of the dryer by permitting a faster circulation or'the drying medium.

A still further object of the present invention is to provide a novelself-cleaning screen having the features and characteristics ser forthabove which is relatively inexpensive both in original cost and inmaintenance cost and is highly eiiicient and effective in operation anduse.

These and other objects of the present invention and the variousfeatures and details of the operation and construction thereof arehereinafter more fully set forth and described with reference to theaccompanying draw-l ings, in which:

Fig. l is a side elevational view of a dryer having the self-cleaningscreen of the present invention incorporated therein;

Fig. 2 is an end elevational view of the dryer illustrated in Fig. l;

Fig. 3 is an enlarged longitudinal sectional View of a pluralcompartment dryer similar to the dryer illustrated in Fig. l;

Fig. 4 is an enlarged longitudinal sectional view of the screen andscreen operating mechanism;

VlFig. 5 is a transverse sectional View taken on line 5 5, Fig. 3illustrating the mounting of the self-cleaning screen in relation to theconveyor carrying the material through the dryer;

Fig. 6 is a fragmentary sectional View taken on line 6 6, Fig. 3;

Fig. 7 is an enlarged fragmentary transverse sectional view taken online 7 7, Fig. 4 illustrating the means for mounting the self-cleaningscreen of the present invention;

Fig. 8 is a plan view of a dryer illustrating a modified arrangement ofthe mechanism for operating the selfcleaning screen; and,

Fig. 9 is a side elevational view partially in section of the dryer andscreen operating mechanism illustrated in Fig. 8.

The present invention consists essentially of providing a reciprocatingscreen or screens in a dryer or other material treating apparatus havinga material treating medium circulating in opposite directions throughadjacent sections of the material being treated. The screens are mountedso that each portion of the screen is moved back and forthlongitudinally of the material treating apparatus between compartmentsor sections of the apparatus having the treating medium circulating inopposite directions. in this manner one section of the screen isinitially in a position in the path of travel of the me- @lum after themedium passes through the material being treated and thus screens outany particles of the material being treated which are en "ained in themedium. That section of the screen is then moved to a position in theapparatus wherein the medium is traveling in the opposite direction andthe particles of material on the screen are blown or forced haelt intothe bed of material being treated.

This type of screen is particularly adaptable for use in apparatus fordrying and conditioning cut tobacco where the drying medium is blownthrough a bed of cut tobacco carried by a foraminous conveyor since thesmall particles of tobacco have a tendency to become entrained in thestream of drying medium passing through the bed of tobacco. in addition,a brush or similar device may be mounted adjacent one end of the dryerhousing to remove particles of material from the screen as it isprojected out from the end of the dryer housing. By this constructionset forth above, particles of the material be* ing dried which are takenout of the stream of drying medium by the screen are continuouslyremoved from the screen and returned to the bed of material thuspreventing clogging or" the screen and the resultant decrease inemciency of the dryer.

Referring new to the drawings and particularly Figs. l and 2 thereof,the present invention is illustrated for use in conjunction with a dryerhut it is apparent that the self-cleaning screens may be used with anytype of material treating apparatus wherein a treating medium is forcedin opposite directions through a bed of material. Reference numeral l()designates generally a. dryer of conventional construction comprising ahousing l1 divided into a plurality of compartments l2 by baiiles orsimilar members 13 extendinu transversely of the dryer housing.

The upper run of a conveyor l of conventional forarninous constructionpasses longitudinally through the dryer housing Li substantially at themidpoint of the compartments 12. The conveyor l. is mounted to ride ontracks 15, 15 at the opposite side edges of the drying chamber, forexample, as illustrated in Fig. 2, and overlapping side guards or plates16 mounted at the opposite sides of the conveyor 14 form a trough-likeupper surface on the conveyor which receives and supports a bed of anydesired thickness of the material to be dried.

In a dryer of this type the drying medium is circulated in oppositedirections in adjacent compartments of the dryer so that the dryingmedium passes downwardly through the bed of material to be dried duringa portion of the drying cycle and upwardly through the bed of materialduring the remaining part of the drying cycle. ln the illustratedembodiments of the present invention the drying medium is passed upthrough the conveyor and the material being dried in the iirstcompartment and in the opposite direction in the next adjacentcompartment. To accomplish this a conventional blower 17 is mounted ineach compartment as shown in Fig. l to cause the desired circulation ofthe drying medium. In addition, heating elements 18 are also providedlongitudinally of the dryer housing l1 to condition and heat the dryingmedium prior to passage through the material being dried.

In accordance with the present invention, means are provided to removeany particles of material which be come entrained in the drying mediumpassing upwardly in the dryer housing through the bed of material beingdried. One form of apparatus for accomplishing this is illustrated inFigs. l to 7, inclusive of the drawings. ln this embodiment a foraminousscreen 2l of any conventional construction comprising a series of screensections 22 is mounted interiorly of the dryer housing 11. A pair oftracks 23, 23 disposed at opposite sides of the dryer housing mount thescreen 21 a short distance above the upper run of the conveyor 14 inspaced parallel relation therewith. Rollers 24,24 mounted adjacent theedges of the screen frames 25 in engagement with the tracks support thescreen in this position and permit free longitudi- Vnal movement of thescreen relative to the dryer housing.

As set forth previously, an important feature of the present inventionis the provision of means to continu- 'ously remove from the' screen theparticles of material being dried which are filtered out of the streamof dr ing medium passing through the bed of material. To this end, thescreen 21 is of a length substantially equal to the length of the dryerhousing and is mounted for reciprocating movement back and forth from arearward limit position interiorly of the housing adjacent the dischargeend thereof to a forwardlimit position toward the feed end of thehousing a distance equal to the longitudinal length of one of thecompartments 12. By this construction the section of the screen adjacentthe discharge end of the housing has the drying medium forced downwardlytherethrough when the screen is in its rearward limit position whichremoves any particles of the material being dried from the screen; andin the forward limit position thereof is positioned in the next to lastcompartment of the dryer housing where theY drying medium is forcedupwardly through the screen so that the screenrremoves all particles ofmaterial from the stream of drying medium. Each other section of thescreen except the section adjacent the feed end of the dryer housing isalternately moved from a position whereinthe drying medium is forcedupwardly through the yscreen to a position wherein the drying mediumpasses downwardly through the screen and removes the particles ofmaterial therefrom. Y

Thersection of screen adjacent the feed end of the dryer housing has thedrying medium blown upwardly therethrough when the screen is in itsrearward limit position and is projected forwardly of the feed end ofthe housing during movement of the screen to its forward limit position.brush 26 extends transversely of the dryer housing adjacent the feed endthereof and is continuously rotated, for example, by means of a smallelectric motor 27 and a chain drive 28. When the screen is projectedforwardly of the feed Vend of the housing the brush engages the lowersurface of the screen thus removing any particles To clean the feed endof the screen a therein and the drying medium passes upwardly through"the bed of material and then through the screensrin the the pinions iscaused by a reversible motor 33 and suit-V able driving connections, forexample, as indicated at 34 in Fig. 2. Rotating the pinions onedirection ywith respect to Fig. 3 will cause the screen to move to itsforward limit position in the dryer housing and rotating the pinions inthe oposite direction will move the screen'to its rearward limitposition. Reversing the direction Vof travel of the screen is controlledby forward and rearward limitswitches 35 and 36, respectively, which aremounted on one of the tracks 23 and are operable to be engaged andactuated by a switch actuating member 37 carried by the screen frame25.- As the screen reaches the end of its forward stroke the switchactuating member 37 engages the forward limit switch 35 thus reversingthe motor 33 and causing the screen to move toward its rearward limitposition. ln a similar manner when the screen reaches its rearward limitposition the switch actuating member 37 engages the rearward limitswitch 36 again reversing the motor 33 and causing the screen to move toits forward limit position.

Various modifications of the screen arrangement may be made depending onthe arrangement of ow of the drying medium in the housing. For example,if the flow of drying medium is down the first compartmentl and up inthe last compartment, the cleaning brush 26 will be mounted adjacent thedischarge end of the dryer housing and the screen will be projectedrearwardly of the discharge end of the housing.` Also, if the ow ofdrying medium is down in both the first and last compartments, thescreen may be made shorter than the dryer housing by a length equal tothe length of one of thecompartments and the screen may be'reciprocatedback and forth in the housing from one end thereof to the other thuseliminating any necessity for a cleaning brush.

Figs. 8 and 9 illustrate a modified form of screen arrangement in thepresent invention Vwherein separate sfreen sections 41 and 42 aremounted for movement independent of one another on separate pairs oftracks 43 and 44, respectively. In addition separate drive mechanism isprovided for each screen Vsection and the screen 41 is reciprocated backand forth in the dryer housing by means of a reversible motor 45 drivinga drum 46' mounted on fixed shaft 47. A cable 48 passes about theV drum46 and has its ends secured to opposite ends of the screen section 41.In addition, resilient tensioning Vmeans is provided in the cable asindicated at 49. When ltheV of the cable 53 are secured to opposite endsof the screen 42, and resilient tensioning means are provided in thecable 53 as indicated at 54. Driving the motor 51 in opposite directionscauses movement of the screen 42 back and forth in the dryer housing.The dryer illustrated in Figs'. 8 and 9 has two separate compartments 55and 56 forward compartment 55, and downwardly throughV the screens andbed of materialto be dried in the rear cornat least one screen to bepositioned in the pathofrthe www drying medium in the compartment 55 atall times, For example, with reference to Fig. 9 at the beginning of onecycle of operation the screen 42 is in the path of the drying mediumpassing upwardly through the bed of material to be dried. The screen 41is then moved to the feed end of the housing and when it reaches thisposition engages and actuates a limit switch 57 which causes operationof the motor 51. The motor 51 will then move the screen 42 to thedischarge end of the dryer housing wherein the drying medium will beforced downwardly through the screen to clean the same. Upon reachingthe discharge end of the dryer housing the screen 42 engages andactuates a limit switch 5S to reverse the operation of the motor 51 andcause the screen 42 to be moved to the feed end of the housing. Uponreaching the feed end of the housing screen 42 engages and actuates athird limit switch 59 which causes operation of the motor 45 thereby'moving the screen 41 to the discharge end of the housing where it iscleaned by the drying medium passing downwardly therethrough. When thescreen 4i reaches the discharge end of the housing a fourth limit switch61 is engaged and actuated by the screen 4l reversing the operation ofthe motor 45 and causing the screen 41 to be moved toward the feed endof the housing. This opration set forth above is repeated continuouslywhile material is passing through the dryer housing and thus the screens41 and 42 will remove any particles of the material being dried from thedrying medium passing upwardly through the bed of material in thecompartment 55 and the screens will be cleaned in the compartments 56and then return to the compartment 55.

From the foregoing it is apparent that the present invention provides anovel self-cleaning screen for dryers and similar apparatus whichremoves any particles of the material being treated which are entrainedin the drying medium passing through the material thus permitting anincrease in the rate of flow of the drying medium with a resultantincrease in the output of the apparatus, .in addition the presentinvention provides a novel continuously operating self-cleaning screenwherein the particles of material caught by the screen are automaticallyremoved therefrom and redeposited on the bed of material being treated.

While particular embodiments of the present invention have beenillustrated and described herein it is not intended to limit theinvention to such a disclosure and changes and modifications may beincorporated and embodied therein within the scope of the foilowingclaims:

I claim:

l. A seif cleaning screen for dryers and similar equipment comprising; ahousing, conveyor means passing through said housing, blower meansoperable to force a treating medium through the conveyor means inopposite directions in adjacent portions of the housing, a plurality ofscreen sections mounted in said housing in spaced parallel relation withsaid conveyor, said screen sections being mounted in adjacent portionsof said housing whereby the treating medium is caused to pass inopposite directions through said adjacent screen sections and saidconveyor, and drive means operable to actuate said screen sections tothe next adjacent portion of the housing wherein treating medium isforced therethrough in the opposite direction.

2. A self cleaning screen for dryers and similar equipment comprising; ahousing, conveyor means passing through said housing, blower meansoperable to force a treating medium through the conveyor means inopposite directions in adjacent portions of the housing, a plurality ofscreen sections positioned in said housing in spaced parallel relationwith said conveyor, means mounting said screen sections forreciprocating movement relative to said housing, said screen sectionsbeing mounted in adjacent portions of said housing whereby the treatingmedium is caused to pass in opposite directions through said adjacentscreen sections, and drive means operable to actuate said screensections and said conveyor in one direction to the next adjacent portionof the housing wherein the treating medium is forced therethrough in theopposite direction and then actuate said screen sections baci; to theiroriginal position in the housing.

3. A self cleaning screen for dryers and similar equipment comprising; ahousing, conveyor means passing through said housing, blower meansoperable to force a treating medium through the conveyor means inopposite directions in adjacent portions of the housing, a plurality ofscreen sections positioned in said housing above said conveyor in spacedparallel relation therewith, means mounting said screen sections in saidhousing for reciprocal movement between forward and rearward limitpositions, said adjacent screen sections being mounted in adjacentportions of said housing whereby the treating medium is caused to passin opposite directions through said adjacent screen sections and saidconveyor, and drive means operable to reciprocate said screen sectionsbaci; and forth between said forward limit positions wherein the screensections are coextensive with one portion of the housing and saidrearward limit position wherein said screen sections are coextensivewith the next adjacent portion of said housing whereby the treatingmedium is successively passed in opposite directions through said screensections.

4. A self cleaning screen for dryers and similar equip ment operable toremove particles of material from a stream of treating medium passingthrough a bed of material being dried and return the particles to thebed of material comprising; a housing including a plurality of separatesections, a foraminous conveyor passing through the housing operable toconvey the bed of material therethrough, blower means to circulate thetreating medium through the material carried by said conveyor, saidmedium being circulated in one direction through the material in onesection of the housing and in the opposite direction through thematerial in the next adjacent section of the housing, a plurality ofscreen sections mounted in said housing in spaced paraliel relation withsaid conveyor, said adjacent screen sections being mounted in adjacentsections of said housing whereby the treating medium is caused to passin opposite directions through said adjacent screen sections and saidconveyor, and drive means operable to actuate said screen sections tothe next adjacent screen of the housing wherein the treatinfI medium isforced therethrough in the opposite direction.

5. A self cleaning screen for dryers and similar equipment operable toremove particles of material from a stream of treating medium passingthrough a bed of material being dried and return the particles to thebed of material comprising; a housing including a plurality of separatesections, a foraminous conveyor passing thro h the housing operable toconvey the bed of material therethrough, blower means to circulate thetreating medion through the material carried by said conveyor, saidmedium being circulated in one direction through the material in onesection of the housing and in the oppl :itc direction through thematerial in the next adjacent section of the housing, a screensubstantially equal to the length of the housing comprising a pluralityof screen sections equal in number to said plurality ot' hous- "iigsections, means mounting said screen in Said housing for reciprocalmovement between one predetermined limit position wherein the screen isentirely within said housing a second predetermined limit Vposition'wherein one screen section is projected beyond one end of housing andeach other screen section is moved to toe next adjacent section of thehousing, and drive means operable to reciprocate said screen back andforth between said predetermined limit positions.

6. A self cleaning screen for dryers and similar equi ment operable toremove particles of material from a stream of treating medium passingthrough a bed of materiai being dried and return the particles to thebed screen sections equal in number to said plurality of hous- Y ingsections, a pair of spaced parallel track members mounted adjacentopposite sides of said housing above said conveyor, rollers on saidscreen in engagement with said tracks mounting said screen insaidhousing for reciprocal movement between one predetermined limit positionwherein the screen is entirely within said housing and a secondiVpredetermined limit position wherein one screen section is projectedbeyond one end of said housing and each other screen section is moved tothe next adjacent section of the housing, and drive means operable toreciprocate said screen back and forth between saidpredetermined limitpositions.

7. A self cleaning screen for dryers and similar equipment operable toremove particles of material from a stream of treating medium passingthrough a bed of materialbeing dried and return the particles to the bedof material comprising; a housing including a plurality of separatesections, a foraminous conveyor passing through Ythe housing operable toconvey the bed of material therethrough, blower means to circulate thetreating medium through the material carried by said conveyor, saidmedium being circulatedv in one direction through the material in onesection of the housing and in the opposite direction through thematerial in the next adjacentrsection of the housing, a screensubstantially equal to the length of the housing comprising a pluralityof screen sections equal in number to said plurality of housingsections, means mounting said screen in said housing for reciprocalmovement between one predetermined limit position wherein the screen isentirely within said housing and a second predetermined limit positionwherein one screen section is projected beyond one end of said housingand each other screen section is moved e to the next adjacent section ofthe housing, driveimeans operable to reciprocate said screen back andforth between said predetermined limit positions, and a rotatable brushmember mounted adjacent said one end of said housing operable to engagesaid screen during movement thereof to said second limit position andremove any particles of mate ial from the screen.

8.' A self cleaning screen for dryers and similar equipment operable toremove particles of material from a stream of treating medium passingthrough a bed of material being treated and return the particies to thebed of material comprising; a housing, means dividing the housing into aplurality of interconnected transverse compartments, a foraminousconveyor extending longitudinaily through the housing operable to conveythe bed of material through each of said compartments, blower meansoperable to circulate the treating medium down through the materialcarried by the conveyor in one compartment and in the opposite directionin the next adjacent compartment, a plurality of screen sections mountedin said housing in spaced parallel relation with said conveyor, saidadjacent screen.. sectionsl being mounted in and coextensivewith'adja'cent compartments in said housing whereby the treating mediumis caused to pass in opposite directions through said adjacent screensections, and drive means operable to actuate said screen sections tothe nextadjacent compartment of the housing wherein the treatingmediumis forced therethrough in the opposite direction.

Y9. A self cleaning screen for dryers and similar equipment operable toremove particles of material from a stream of treating medium passingthrough a vbed of material being treated and return the particles to thebed of material comprising; a housing, means dividing theY housing intoa plurality of interconnected transverse.v

compartments, a foraminous conveyor extending longitudinally through thehousing operable to convey the bed ofrnaterial through each of saidcompartments, blower means operable to circulate the treating mediumdown through the material carried by the conveyor in'one com artment andin the opposite directionin the next adjacent compartment, a screensubstantially equal to the length of the housing comprising a pluralityof screen sections equal in number to said plurality of housingcompartments, means mounting said Screen inY said housing for reciprocalmovement between one predetermined limit position wherein the screen isentirely within said housing and a second predetermined limit positionWherein one screen section is projected beyond one end of said housingand each other screen section is moved to the next adjacent compartmentof the housing, and drive means operable to reciprocate said screen backand forth between said predetermined limit positions. Y

lt). A self cleaning screen for dryers and similar equipment operable toremove particles of material from a stream of treating medium passingthrough a bed of material being treated and return the particles to thebed of material comprising; a housing, means dividing the housing into aplurality of interconnected transverse compartments, a foraminousconveyor extending longitudinally through the housing operable to conveythe bed of material through each of saidV compartments, blower meansoperable to circulate the treating medium down V'through the materialcarried by the conveyor in one compartment and in the opposite directionin the next Y adjacent compartment, a screen substantially equal to thelength of the housing comprising a plurality of screen sections equal innumber to said plurality of housing compartments, a pair of spacedparallel track members mounted adjacent opposite sides of said housingabove said conveyor, rollers on said screen in engagement with saidtracks mounting said screen in said housing for reciprocal movementVbetween one predetermined limit position wherein the screen is entirelyWithin said housing and a second predetermined limit position whereinone screen section is projected beyond one end of said housing and eachother screen section is moved to the next adjacent compartment of thehousing, drive means operable to reciprocate said screen back and forthbetween said predetermined limit positions, and a rotatable brush membermounted adjacent said one end of said housing operable to engage saidscreen during movement thereof to Vsaid other limit position and removeany particles of material from the screen.

ll. A self cleaning screen for dryers and similar,VY Y equlpmentcomprising, aV housing, conveyor means passing through said housing,blower means operable to force a treating medium through the conveyormeans in opposite directions in adjacent portions of the housing, afirst screen section mounted in one portion of said housing forreciprocal movement between said one portion of the housing to the nextadjacent portion of the housing, a second screen section mounted in saidnext adjacent portion ot the housing for reciprocal movement from saidportion to said one portion of the housing, and drive means operable toreciprocate said screen sections back and forth between said housingportions.

l2. A self cleaning screen for dryers and similar equipment operable toremove particles of material from a stream of treating medium passingthrough a bed of material being treated Yand return theparticles to thebed of material comprising; a housing, means dividing the` bed ofmaterial through each or" said compartments, blower means operable tocirculate the treating medium down through the material carried by theconveyor in one compartment and in the opposite direction in the nextadjacent compartment, a rst screen section coextensive with one of saidhousing compartments, a second screen section coextensive with said nextadjacent housing compartment, means mounting said screen sections forreciprocal movement back and forth between said rst and said nextadjacent housing compartments, and drive means operable to reciprocatesaid screen sections back and forth in said housing.

13. A self cleaning screen for dryers and similar equipment operable toremove particles of material from a stream of treating medium passingthrough a bed of material being treated and return the particles to thebed of material comprising; a housing, means dividing the housing into aplurality of interconnected transverse compartments, a foraminousconveyor extending longitudinally through the housing operable to conveythe bed of material through each of said compartments, lower meansoperable to circulate the treating medium down through the materialcarried by the conveyor in one cornpartment and in the oppositedirection in the next adjacent compartment, a rst screen sectioncoextensive with one of said housing compartments, a second screensection coextensive with said next adjacent housing compartment, meansmounting said screen sections for reciprocal movement back and forthbetween said rst and said next adjacent housing compartments, drivemechanism for each of said screen sections operable to reciprocate thesame back and forth between said housing compartments, and controlmechanism actuated by movement of said screen sections operable toactuate said drive mechanism.

References Cited in the file of this patent UNITED STATES PATENTS1,026,432 Dey May 14, 1912 1,361,626 Schwartz et al. Dec. 7, 19202,216,986 Roe Oct. 8, 1940 FOREIGN PATENTS 182,007 Germany Mar. 5, 1907871,076 France Jan. 3, 1942

